(1) Field of the Invention
The present invention relates to a continuously advancing machine for leveling, lining and tamping a railroad track, which comprises a main frame extending longitudinally in the direction of the track and a tool-carrying frame longitudinally displaceably connected with the main frame. At least one respective undercarriage supports the main frame and the tool-carrying frame, the tool-carrying frame supporting undercarriage being spaced from the main frame supporting undercarriage a sufficient distance to permit free displacement of the track during leveling and lining. Drive means is connected to the main frame supporting undercarriage for continuously advancing the main frame in an operating direction and a brake is connected to the main frame supporting undercarriage for stopping the advancing main frame. An operator's cab, a control arrangement and a power plant are mounted on the continuously advancing main frame, and a drive means intermittently advances the tool-carrying frame on which there are mounted track leveling and lining and tie tamping tool means within sight of the operator's cab, the tool means including drives for operating the tool means and the drives being actuated by the control arrangement. A track position reference system is connected to the control arrangement for actuating the drives of the track leveling and lining tools in response to the track position detected by the reference system.
(2) Description of the Prior Art
U.S. Pat. Ser. No. 4,627,358, dated Dec. 9, 1986, discloses such a continuously advancing track leveling, lining and tamping machine which has had outstanding commercial success. This machine comprises an elongated, bridge-like main frame supported by widely spaced undercarriages, one of which has a drive and brake means for continuously advancing and stopping the main frame, the main frame carrying a control arrangement and power plant, and a tool-carrying frame arranged between the undercarriages. One end of the tool-carrying frame is supported on the track by a pair of guide wheels constituting an undercarriage for the tool-carrying frame and an opposite tool-carrying frame end is universally joined to the main frame, track leveling and lining tool and tie tamping tool means being mounted on the tool-carrying frame, and the tool-carrying frame and the tool means supported thereon constituting an operating unit longitudinally displaceable relative to the main frame. A hydraulically operated cylinder-piston drive intermittently advances the operating unit. For controlling the leveling and lining operations and assuring an accurate track position correction, a track position reference system is associated with the control arrangement. Since the rear end of the tool-carrying frame is supported on the track by the guide wheels immediately adjacent the tie tamping tool means, a considerable portion of the weight and operating forces of the tool means is transmitted to the track during advancement of the machine. Therefore, the main frame, which advances continuously while the tool-carrying frame advances intermittently, is subjected to a minimum of static and dynamic forces. If a cab for an operator of the tool means is arranged on the main frame, the operator's working conditions will be much improved since he will not be subjected to the impacts and vibrations of the tool means during their operation. This structure for the first time provided a practical tie tamping technology in which the cyclic tie tamping operation is effected on a continuously advancing machine.
U.S. Pat. Ser. No. 4,632,037, dated Dec. 30, 1986, discloses a further development of this continuously advancing track leveling, lining and tamping machine, in which the undercarriage supporting the tool-carrying frame has its own drive and brake means for intermittently advancing the tool-carrying frame. In some embodiments, the tool-carrying frame is supported by two widely spaced undercarriages to form a satellite carriage. The track leveling and lining tool and tamping tool means precede, and are within sight of, an operator's cab mounted on the main frame. Furthermore, a hydraulically operated cylinder-piston drive for stop-and-go advancement of the tool-carrying frame links the tool-carrying frame to the main frame, and this drive may be operated to block relative movement between the frames so that they will advance in unison. This machine, too, has been used very successfully, the independent drive and brake arrangement for the tool-carrying frame assuring an improved and trouble-free relative displacement between the frames during operation of the machine.
U.S. Pat. Ser. No. 4,643,101, dated Feb. 17, 1987, also discloses a further development of such a continuously advancing track leveling, lining and tamping machine, in which the main frame and the tool-carrying frames are linked to each other and each is supported on two undercarriages. A hydraulically operated cylinder-piston drive is arranged to displace the tool-carrying frame longitudinally relative to the main frame to enable the tool-carrying frame to advance intermittently while the main frame advances continuously. A vertically adjustable track stabilizer including vibrating means and means for laterally pivoting the track stabilizing tools is mounted on the main frame between the undercarriages thereof and this track stabilizer is equipped with its own track leveling reference system. As is known, such track stabilizers anticipate the settling of the tamped track under the loads of passing trains and also enhance the resistance to transverse movements of the ties by firmly embedding the ties in the settled ballast to keep the track accurately lined.
Swiss patent No. 648,621, granted Mar. 29, 1985, discloses an intermittently advancing tie tamping machine comprising a frame whose two ends are supported by undercarriages. Track leveling and lining tool and tie tamping tool means are mounted on the machine frame between the two undercarriages. Respective driver's cabs are arranged at the front and rear ends of the machine frame, the front cab serving also as an operator's cab and being longitudinally displaceable on the machine frame by a hydraulical cylinder. During operation, the machine advances intermittently from tie to tie and, while the machine stands still during each tie tamping cycle, the operator's cab continues to advance. When the machine advances again to the next tie to be tamped, the operator's cab is displaced relative to the machine frame in a direction opposite to that of the machine advance, the displacement path being measured by a vertically adjustable odometer. The purpose of this structure is to assure a steady and continuous forward movement for the operator during the intermittent tamping operation. However, the entire heavy machine, except for the relatively light cab, still advances intermittently, which requires the considerable driving and braking forces involved in this intermittent movement wherefore the total efficiency of this tie tamper is no greater than that of the conventional, intermittently advancing tampers in which the operator's cab moves in unison with the machine frame. Nor does it have any particular advantage to make the operator's cab freely transversely displaceable and to guide it on flanged wheels, one of which is driven, along the track rails since the entire power train still operates to advance the machine intermittently. Therefore, this type of tie tamper has found no commercial acceptance.
Finally, U.S. Pat. Ser. No. 4,165,694, dated Aug. 28, 1979, discloses an intermittently advancing track leveling, lining and tamping machine comprising a main frame supported by two undercarriages at respective ends thereof. Track leveling and lining tool and tie tamping tool means are vertically adjustably mounted on the main frame between the undercarriages. An auxiliary frame precedes the main frame in an operating direction and a rear end thereof is coupled to the front end of the main frame by a hydraulic drive for longitudinally displacing the auxiliary frame relative to the main frame while the front end of the auxiliary frame is supported on the track by an undercarriage. A ballast plow is vertically adjustably mounted on the auxiliary frame between the front undercarriage and the longitudinal displacement drive for the auxiliary frame. While the main frame advances intermittently during the tamping operation and stands still each time a tie is tamped, the hydraulic drive displaces the auxiliary frame relative to the main frame so that the ballast plow advances continuously. This arrangement provides more uniform ballasting and, therefore, improves the tie tamping quality but the efficiency of such a machine is no greater than that of the conventional, intermittently advancing track leveling, lining and tamping machine.